/in/foo.cc: In function 'int main()':
/in/foo.cc:9:19: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   cout<<28+(y%4==0&&y%100!=0||y%400=0);
             ~~~~~~^~~~~~~~~~
/in/foo.cc:9:37: error: lvalue required as left operand of assignment
   cout<<28+(y%4==0&&y%100!=0||y%400=0);
                                     ^